From a204b5fac497e2ffbc6791f0f7de9d9d12c16d52 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Fri, 5 Mar 2021 01:27:52 +0200
Subject: [PATCH] Remove unused type declarations from GLSL during optimization

The biggest impact of this right now is keeping the AST dump manageable.
---
 source/glsl/compiler.cpp |  1 +
 source/glsl/optimize.cpp | 34 ++++++++++++++++++++++++++++++++--
 source/glsl/optimize.h   | 16 ++++++++++++++++
 3 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/source/glsl/compiler.cpp b/source/glsl/compiler.cpp
index 0f608d6d..172bdac6 100644
--- a/source/glsl/compiler.cpp
+++ b/source/glsl/compiler.cpp
@@ -286,6 +286,7 @@ Compiler::OptimizeResult Compiler::optimize(Stage &stage)
 	to become unused. */
 	bool any_removed = UnusedVariableRemover().apply(stage);
 	any_removed |= UnusedFunctionRemover().apply(stage);
+	any_removed |= UnusedTypeRemover().apply(stage);
 
 	return any_removed ? REDO_PREVIOUS : any_inlined ? REDO_STAGE : NEXT_STAGE;
 }
diff --git a/source/glsl/optimize.cpp b/source/glsl/optimize.cpp
index 137bd943..88a32399 100644
--- a/source/glsl/optimize.cpp
+++ b/source/glsl/optimize.cpp
@@ -622,6 +622,38 @@ UnusedVariableRemover::VariableInfo::VariableInfo():
 { }
 
 
+bool UnusedTypeRemover::apply(Stage &stage)
+{
+	stage.content.visit(*this);
+	NodeRemover().apply(stage, unused_nodes);
+	return !unused_nodes.empty();
+}
+
+void UnusedTypeRemover::visit(BasicTypeDeclaration &type)
+{
+	if(type.base_type)
+		unused_nodes.erase(type.base_type);
+	unused_nodes.insert(&type);
+}
+
+void UnusedTypeRemover::visit(ImageTypeDeclaration &type)
+{
+	if(type.base_type)
+		unused_nodes.erase(type.base_type);
+	unused_nodes.insert(&type);
+}
+
+void UnusedTypeRemover::visit(StructDeclaration &strct)
+{
+	unused_nodes.insert(&strct);
+}
+
+void UnusedTypeRemover::visit(VariableDeclaration &var)
+{
+	unused_nodes.erase(var.type_declaration);
+}
+
+
 UnusedVariableRemover::UnusedVariableRemover():
 	aggregate(0),
 	r_assignment(0),
@@ -760,7 +792,6 @@ void UnusedVariableRemover::visit(ExpressionStatement &expr)
 void UnusedVariableRemover::visit(StructDeclaration &strct)
 {
 	SetForScope<Node *> set(aggregate, &strct);
-	unused_nodes.insert(&strct);
 	TraversingVisitor::visit(strct);
 }
 
@@ -774,7 +805,6 @@ void UnusedVariableRemover::visit(VariableDeclaration &var)
 		if(var.init_expression)
 			record_assignment(var, *var.init_expression, false);
 	}
-	unused_nodes.erase(var.type_declaration);
 	TraversingVisitor::visit(var);
 }
 
diff --git a/source/glsl/optimize.h b/source/glsl/optimize.h
index c932767e..85f11780 100644
--- a/source/glsl/optimize.h
+++ b/source/glsl/optimize.h
@@ -165,6 +165,22 @@ private:
 	virtual void visit(Iteration &);
 };
 
+/** Removes types which are not used anywhere. */
+class UnusedTypeRemover: private TraversingVisitor
+{
+private:
+	std::set<Node *> unused_nodes;
+
+public:
+	bool apply(Stage &);
+
+private:
+	virtual void visit(BasicTypeDeclaration &);
+	virtual void visit(ImageTypeDeclaration &);
+	virtual void visit(StructDeclaration &);
+	virtual void visit(VariableDeclaration &);
+};
+
 /** Removes variable declarations with no references to them.  Assignment
 statements where the result is not used are also removed. */
 class UnusedVariableRemover: private TraversingVisitor
-- 
2.43.0